This document reviews previous investigations and proposes research related to topics in the processing of visual items. The proposed experiments use reaction-time and accuracy data in the context of three experimental tasks. In one task, subjects first learn about a set of pictures. Then, for each of a series of trials, they prepare for a given picture, then make a decision about a visual display which may or may not contain that picture. In another task, subjects are taught that a certain aspect of visual items is relevant or irrelevant to a response decision. They then transfer to a new task where that critical aspect is to be ignored, and the effect of its previous relevance is assessed. The third task requires subjects to make two consecutive semantic decisions about common objects. The data from these tasks are used to address the following questions: (1) To what extent does the nature of an actively processed stimulus representation depend on previously acquired knowledge? (2) What is the nature of long-term knowledge about categories of visual items? (3) How do representations of visual information in memory compare to corresponding verbal representations?